Monolithic capacitor mounting structure and monolithic capacitor

ABSTRACT

In a monolithic capacitor mounting structure, assuming that a portion of a first outer electrode joined with a first bonding material is a first bonding portion and a portion of a second outer electrode joined with a second bonding material is a second bonding portion, a length of each of the first and second bonding portions in a lengthwise direction of the monolithic capacitor is about 0.2 times to about 0.5 times a length of an elementary body in the lengthwise direction, and a center of each of the first and second bonding portions in the lengthwise direction is located at a position different from a center of the elementary body in the lengthwise direction. Vibration noise is changed depending on positions of outer electrodes of the monolithic capacitor, the outer electrodes being used to bond the monolithic capacitor to a mounting substrate.

CROSS REFERENCE

This non-provisional application claims priority under 35 U.S.C. §119(a)to Patent Application No. 2012-177638 filed in Japan on Aug. 10, 2012,and Patent Application No. 2012-177639 filed in Japan on Aug. 10, 2012,the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mounting structure of a monolithiccapacitor including outer electrodes on an elementary body that includesdielectric layers and inner electrodes, which are alternately stacked,and also relates to a monolithic capacitor mounted in the mountingstructure.

2. Description of the Related Art

At present, monolithic capacitors are widely utilized in variouselectronic devices, including cellular phones and other mobileterminals, personal computers, etc. The monolithic capacitor includes anelementary body having a substantially rectangular parallelepiped shapeand functioning as a capacitor. The elementary body has a structure inwhich dielectric layers and electrodes (inner electrodes), each being inthe form of a flat plate, are alternately stacked. That type ofmonolithic capacitor includes outer electrodes connected to the innerelectrodes. The outer electrodes are generally formed at both ends ofthe elementary body in the lengthwise direction thereof, respectively.

The above-described monolithic capacitor is electrically and physicallyconnected to a circuit board of an electronic device by directly placingthe outer electrodes on mounting lands of the circuit board, and bybonding the mounting lands and the outer electrodes to each other usinga bonding material, e.g., solder.

When an AC voltage or a DC voltage superimposed with an AC voltage isapplied to the monolithic capacitor, vibration is generated withmechanical distortion due to the piezoelectric or electrostrictiveeffect. In particular, when a ceramic having a high dielectric constant,such as barium titanate, is used as a dielectric of the monolithiccapacitor, the vibration caused by mechanical distortion of themonolithic capacitor is increased. When the vibration is generated inthe monolithic capacitor, the generated vibration is transmitted to thecircuit board, thus causing the circuit board to vibrate. The vibrationof the circuit board may cause vibration noise that is perceptible bythe human ear.

To solve the above-mentioned problem, Japanese Unexamined PatentApplication Publication No. 8-55752, for example, discloses thefollowing technique. A monolithic capacitor is mounted to a substrate insuch a state that surfaces of inner electrodes are orientedperpendicularly to the surface of the substrate. With such anarrangement, even when dielectric ceramics vibrate upon application of avoltage while repeating expansion and restoration in the direction ofthickness thereof (i.e., the direction in which the inner electrodes arestacked), the vibration is not directly transmitted to the substrate,whereby vibration noise can be reduced.

However, the monolithic capacitor vibrates not only in the direction ofthickness thereof, but also in the planar direction of each innerelectrode. Therefore, even when the arrangement disclosed in JapaneseUnexamined Patent Application Publication No. 8-55752 is employed, thevibration is not reduced depending on the types of circuit boards.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a monolithiccapacitor mounting structure and a monolithic capacitor mounted in themounting structure, which significantly reduces and prevents generationof vibration noise.

According to one preferred embodiment of the present invention, amonolithic capacitor mounting structure includes a monolithic capacitorincluding an elementary body having a parallelepiped shape or asubstantially parallelepiped shape and defined by plural dielectriclayers and plural inner electrodes, which are alternately stacked, afirst outer electrode located on a first side surface, extending in alengthwise direction, of the elementary body, and a second outerelectrode located on a second side surface, extending in the lengthwisedirection, of the elementary body, a mounting substrate including aninsulating substrate, a first land electrode disposed on a surface ofthe insulating substrate and connected to the first outer electrode, anda second land electrode disposed on the surface of the insulatingsubstrate and connected to the second outer electrode, a first bondingmaterial arranged to bond the first outer electrode and the first landelectrode, and a second bonding material arranged to bond the secondouter electrode and the second land electrode.

Assuming that a portion of the first outer electrode, the portion beingjoined with the first bonding material, is a first bonding portion and aportion of the second outer electrode, the portion being joined with thesecond bonding material, is a second bonding portion, a length of eachof the first and second bonding portions in the lengthwise direction is,for example, about 0.2 times to about 0.5 times a length of theelementary body in the lengthwise direction, and a center of each of thefirst and second bonding portions in the lengthwise direction is locatedat a position different from a center of the elementary body in thelengthwise direction.

In accordance with various preferred embodiments of the presentinvention, vibration noise can be changed depending on positions of theouter electrodes of the monolithic capacitor, at which the monolithiccapacitor is bonded to the mounting substrate.

With the arrangement according to one preferred embodiment of thepresent invention, by specifying shapes and positions of the bondingportions as described above, the monolithic capacitor can be mounted tothe mounting substrate except at regions where the volume of theelementary body is apt to change due to the piezoelectric orelectrostrictive effect. As a result, generation of the vibration noisecan be significantly reduced or prevented.

In the monolithic capacitor mounting structure according to the onepreferred embodiment of the present invention, the length of each of thefirst and second bonding portions in the lengthwise direction may bewithin a range of about 0.4±0.05 times the length of the elementary bodyin the lengthwise direction, for example.

With the above-described arrangement, the monolithic capacitor ismounted to the mounting substrate in regions where volume change of theelementary body is relatively unlikely to occur. As a result, thegeneration of the vibration noise is significantly reduced or prevented.

Preferably, the first and second bonding portions extending in thelengthwise direction are arranged such that ends of each of the firstand second bonding portions in the lengthwise direction are positionedwithin a range of about 0.25 times the length of the elementary body inthe lengthwise direction from the center of the elementary body in thelengthwise direction, for example.

Furthermore, in the monolithic capacitor mounting structure according tothe one preferred embodiment of the present invention, a distancebetween the center of each of the first bonding portion and the secondbonding portion in the lengthwise direction and the center of theelementary body in the lengthwise direction is preferably within a rangeof about 0.1±0.05 times the length of the elementary body in thelengthwise direction, for example.

These arrangements can significantly reduce or prevent the generation ofthe vibration noise.

According to other preferred embodiments of the present invention,shapes and positions of the first and second outer electrodes, or shapesand positions of the first and second land electrodes may be adjusted inorder to set the shapes and the positions of the first and secondbonding portions as described above.

In addition, the present invention is not limited to monolithiccapacitor mounting structure, and other preferred embodiments of thepresent invention include a monolithic capacitor mounted in theabove-described mounting structure.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external perspective view of a monolithic capacitor to bemounted in a mounting structure according to a first preferredembodiment of the present invention.

FIGS. 2A, 2B, 2C, and 2D are four orthogonal views of the monolithiccapacitor to be mounted in the mounting structure according to the firstpreferred embodiment of the present invention.

FIG. 3 is a perspective view of the monolithic capacitor in a statemounted in the mounting structure according to the first preferredembodiment of the present invention.

FIG. 4 illustrates a distortion distribution caused by applying avoltage to a monolithic ceramic capacitor according to a preferredembodiment of the present invention.

FIG. 5 is a graph representing a vibration noise suppression effect ofthe monolithic capacitor mounted in the mounting structure according tothe first preferred embodiment of the present invention.

FIG. 6 is an external perspective view of a monolithic capacitor to bemounted in a mounting structure according to a second preferredembodiment of the present invention.

FIG. 7 is a graph representing a vibration noise suppression effect ofthe monolithic capacitor mounted in the mounting structure according tothe second preferred embodiment of the present invention.

FIG. 8 is a flowchart illustrating a method for reducing vibration noisegenerated from a mounting substrate in accordance with a preferredembodiment of the present invention.

FIG. 9 is an external perspective view of a mounting substrate in themounting structure according to a third preferred embodiment of thepresent invention.

FIGS. 10A, 10B, and 10C are three orthogonal views of the mountingsubstrate in the mounting structure according to the third preferredembodiment of the present invention.

FIG. 11 is a perspective view illustrating a state in which a monolithiccapacitor is mounted to the mounting substrate in the mounting structureaccording to the third preferred embodiment of the present invention.

FIG. 12 is a graph representing a vibration noise suppression effect ofthe mounting substrate in the mounting structure according to the thirdpreferred embodiment of the present invention.

FIG. 13 is a plan view of a mounting substrate in a mounting structureaccording to a fourth preferred embodiment of the present invention.

FIG. 14 is a graph representing a vibration noise suppression effect ofthe mounting substrate in the mounting structure according to the fourthpreferred embodiment of the present invention.

FIG. 15 is a flowchart illustrating a method for reducing the vibrationnoise generated from a mounting substrate in accordance with a preferredembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A monolithic capacitor to be mounted in a mounting structure accordingto preferred embodiments of the present invention will be describedbelow with reference to the drawings.

FIG. 1 is an external perspective view of a monolithic capacitor 10 tobe mounted in the mounting structure according to the first preferredembodiment of the present invention. FIGS. 2A, 2B, 2C, and 2D are fourorthogonal views of the monolithic capacitor 10 to be mounted in themounting structure according to the first preferred embodiment. FIG. 3is a perspective view of the monolithic capacitor 10 in a state mountedin the mounting structure according to the first preferred embodiment.

The monolithic capacitor 10 preferably includes an elementary body 11,one first outer electrode 21, and one second outer electrode 22. Theelementary body 11 preferably has a rectangular parallelepiped shape ora substantially rectangular parallelepiped shape extending in alengthwise direction, a widthwise direction, and a height direction.Hereinafter, a length of the elementary body 11 in the lengthwisedirection is denoted by LC, and a width of the elementary body 11 in thewidthwise direction is denoted by LCw.

The elementary body 11 is defined by alternately stacking dielectriclayers and inner electrodes 100. The dielectric layers and the innerelectrodes 100 are preferably each in the form of a rectangular orsubstantially rectangular flat plate. The dielectric layers are eachmade of, e.g., a ceramic material, and the inner electrode 100 are eachmade of, e.g., copper (Cu).

Surfaces of the elementary body 11 extending parallel or substantiallyparallel to the lengthwise direction perpendicularly or substantiallyperpendicularly to a stacking direction of the dielectric layers and theinner electrodes 100 serve as a top surface 111 and a bottom surface 112of the elementary body 11. Surfaces of the elementary body 11 extendingparallel or substantially parallel to the lengthwise direction andparallel or substantially parallel to the stacking direction of thedielectric layers and the inner electrodes 100 serve as a firstlengthwise side surface 113 and a second lengthwise side surface 114 ofthe elementary body 11. Surfaces of the elementary body 11 extendingperpendicularly or substantially perpendicularly to the lengthwisedirection, i.e., surfaces of the elementary body 11 extending parallelor substantially parallel to the widthwise direction, serve as a firstwidthwise side surface 115 and a second widthwise side surface 116 ofthe elementary body 11.

Each inner electrode 100 preferably includes a connecting portion 100 min which an electrode end is exposed to the first lengthwise sidesurface 113, or a connecting portion 100 n in which an electrode end isexposed to the second lengthwise side surface 114. For example, theinner electrode 100 including the connecting portion 100 m and the innerelectrode 100 including the connecting portion 100 n are alternatelystacked with the dielectric layer interposed between them.

The inner electrodes 100 are not exposed to the first widthwise sidesurface 115 and the second widthwise side surface 116.

The first outer electrode 21 is preferably arranged at or substantiallyat a center of the first lengthwise side surface 113 of the elementarybody 11. The second outer electrode 22 is preferably arranged at orsubstantially at a center of the second lengthwise side surface 114 ofthe elementary body 11. The first outer electrode 21 and the secondouter electrode 22 preferably have the same length in the lengthwisedirection. A length LD of each of the first and second outer electrodes21 and 22 in the lengthwise direction is preferably shorter than thelength LC of the elementary body 11 in the lengthwise direction.

The first outer electrode 21 and the second outer electrode 22 arepreferably defined over a full height of the first and second lengthwiseside surfaces 113 and 114 in the height direction thereof, respectively.In addition, the first outer electrode 21 and the second outer electrode22 are preferably arranged so as to extend in partly covering relationto the top surface 111 and the bottom surface 112.

The monolithic capacitor 10 having the above-described structure ispreferably mounted to a mounting substrate 90, as illustrated in FIG. 3.

The mounting substrate 90 includes an insulating substrate 90A in theform of a flat or substantially flat plate.

The insulating substrate 90A is preferably made of, e.g., a glass epoxyresin substrate, such as FR-4, for example. A pair of land electrodes 91is defined on one principal surface (front surface) of the insulatingsubstrate 90A.

The monolithic capacitor 10 is mounted to the mounting substrate 90 bybonding the first outer electrode 21 to one of the land electrodes 91and bonding the second outer electrode 22 to the other land electrode91. The bonding is preferably performed using, e.g., a solder 900.

A first bonding portion 902 is a portion of the first outer electrode21, preferably provided on the side surface 113, where the first outerelectrode 21 is joined with the solder 900.

A second bonding portion (not shown, but identical or substantiallyidentical to the first bonding portion 902) is a portion of the secondouter electrode 22, preferably provided on the side surface 114, wherethe second outer electrode 22 is joined with the solder 900.

With the bonding using the solder 900, the monolithic capacitor 10 ismounted to the mounting substrate 90 through the first bonding portion902 and the second bonding portion.

The monolithic capacitor 10 having the above-described structure causesdistortion due to a voltage applied thereto. At least one of thepreferred embodiments of the present invention is able to obtain thefollowing results by analyzing the distortion of the monolithiccapacitor 10 caused due to the applied voltage.

FIG. 4 illustrates a distortion distribution caused by applying avoltage to the monolithic capacitor 10. In FIG. 4, A81, A82, and A83represent regions partitioned depending on an amount of distortion. Arelation in magnitude of the distortion amount among those regions isgiven by A81<A82<A83. In other words, A81 represents the region wherethe distortion is least likely to occur, and A83 represents the regionwhere the distortion is most likely to occur.

As illustrated in FIG. 4, when a predetermined voltage is applied to themonolithic capacitor 10, the top surface 111 and the bottom surface 112are entirely distorted, and the distortion increases toward theircentral regions. On the other hand, the distortion is relatively smallin regions near centers of respective edges of the top surface 111 andthe bottom surface 112, the edges adjoining to the first and secondlengthwise side surfaces 113 and 114.

Furthermore, the distortion is increased near respective both edges ofthe first and second lengthwise side surfaces 113 and 114 of themonolithic capacitor 10 in the lengthwise direction, i.e., nearrespective both edges of the first and second lengthwise side surfaces113 and 114, the edges adjoining to the first and second widthwise sidesurfaces 115 and 116. On the other hand, the distortion is relativelysmall in regions near respective centers of the first and secondlengthwise side surfaces 113 and 114 of the monolithic capacitor 10 inthe lengthwise direction.

Moreover, the distortion is increased in respective central regions, asviewed in the height direction, of both end surfaces of the monolithiccapacitor 10 in the lengthwise direction (i.e., of the first and secondwidthwise side surfaces 115 and 116). The distortion is relatively smallin bottom regions of the first and second widthwise side surface 115 and116, the heights of the bottom regions from the bottom surface 112 beingheight “Hth”.

Based on the foregoing results, according to the first preferredembodiment of the present invention, the first and second outerelectrodes 21 and 22 are arranged at or substantially at the centers ofthe first and second lengthwise side surfaces 113 and 114 of theelementary body 11 in the lengthwise direction, as described above. Withsuch an arrangement, the first and second outer electrodes 21 and 22 arepositioned in the regions of the monolithic capacitor 10 where thedistortion is small. In other words, the monolithic capacitor 10 ismounted to the mounting substrate 90 through the first bonding portion902 and the second bonding portion in the regions of the monolithiccapacitor 10 where the distortion is small. Accordingly, vibrationattributable to the distortion is hardly generated in the mountingsubstrate 90, and the generation of vibration noise can be greatlyreduced or prevented.

Here, the length LD of each of the first and second outer electrodes 21and 22 is preferably within the range discussed below. FIG. 5 is a graphrepresenting the correlation between a ratio of the length LD of each ofthe first and second outer electrodes 21 and 22 to the length LC of theelementary body 11 and a peak vibration level. In FIG. 5, 0.2 LC impliesthat the length LD of each of the first and second outer electrodes 21and 22 is preferably about 0.2 times the length LC of the elementarybody 11, for example. Furthermore, FIG. 5 represents the case where acenter of the elementary body 11 in the lengthwise direction is alignedwith a center of each of the first and second outer electrodes 21 and 22in the lengthwise direction.

Additionally, in FIG. 5, REF1 represents the case where outer electrodesare defined on both end surfaces (corresponding to the first and secondwidthwise side surfaces 115 and 116) of an elementary body in thelengthwise direction thereof (i.e., the case of a general arrangement ofa related-art monolithic capacitor). In that arrangement, the outerelectrodes extend so as to partially cover a top surface, a bottomsurface, and both lengthwise side surfaces of the elementary body fromboth the end surfaces of the elementary body in the lengthwisedirection. REF2 represents the case where outer electrodes are definedon entire lengthwise side surfaces of an elementary body, and the outerelectrodes are each arranged to partially cover a top surface, a bottomsurface, and both widthwise side surfaces of the elementary body fromboth the lengthwise side surfaces of the elementary body. Moreover, FIG.5 represents the result on condition that the length LC of theelementary body 11 in the lengthwise direction is 1.0 mm (i.e., LC=1.0mm), the width LCw of the elementary body 11 in the widthwise directionis about 0.5 mm (i.e., LCw=0.5 mm), and the height of the elementarybody 11 is about 0.5 mm, for example.

As seen from FIG. 5, the peak vibration level can be reduced incomparison with the cases of REF1 and REF2 by setting the length LD ofeach of the first and second outer electrodes 21 and 22 to be shorterthan the length LC of the elementary body 11, and by arranging the firstand second outer electrodes 21 and 22 at the center of the elementarybody 11 in the lengthwise direction.

In addition, as seen from FIG. 5, the peak vibration level has a minimumvalue with respect to the ratio of the length LD of each of the firstand second outer electrodes 21 and 22 to the length LC of the elementarybody 11. In more detail, as illustrated in FIG. 5, the peak vibrationlevel has a minimum value at LD=(0.4±0.05)×LC, i.e., when the length LDof each of the first and second outer electrodes 21 and 22 is about 0.4times the length LC of the elementary body 11, for example. Furthermore,a range where the vibration attributable to the distortion can beregarded as sufficiently small exists within a range of predeterminedlength LD including 0.4 LC and thereabout at which the minimum value isobtained. More specifically, that range is given as a range where thepeak vibration level illustrated in FIG. 5 is smaller than a reducedvalue Th, i.e., a range where the length LD of each of the first andsecond outer electrodes 21 and 22 is about 0.2 to about 0.5 times thelength LC of the elementary body 11, for example. In the first preferredembodiment, the reduced value Th is set to −10 dB of the peak vibrationlevel in the cases of REF1 and REF2. The reduced value Th can beincreased or decreased depending on the situation in use of themonolithic capacitor, but a more satisfactory result is obtained bysetting the reduced value Th to −10 dB.

Thus, the vibration can be greatly reduced by setting the length LD ofeach of the first and second outer electrodes 21 and 22 to fall in therange of about 0.2 to about 0.5 times the length LC of the elementarybody 11, for example. The vibration can be reduced to a larger extent bysetting the length LD of each of the first and second outer electrodes21 and 22 to be about 0.4 times the length LC of the elementary body 11,for example.

A monolithic capacitor to be mounted in a mounting structure accordingto a second preferred embodiment of the present invention will bedescribed below with reference to the drawings. FIG. 6 is a plan view ofa monolithic capacitor 10A to be mounted in the mounting structureaccording to the second preferred embodiment of the present invention.The monolithic capacitor 10A according to the second preferredembodiment is different from the monolithic capacitor 10 according tothe first preferred embodiment in that the positions of the first andsecond outer electrodes 21A and 22A in the lengthwise direction of theelementary body 11 are preferably shifted (displaced). The otherarrangement is preferably the same as that of the monolithic capacitor10 to be mounted in the mounting structure according to the firstpreferred embodiment, and detailed description of the other arrangementis omitted here.

In the monolithic capacitor 10A illustrated in FIG. 6, centers of firstand second outer electrodes 21A and 22A are preferably shifted from thecenter of the elementary body 11 in the lengthwise direction. An amountSS1 of such center shift is about 0.1±0.05 times the length LC of theelementary body 11, for example.

FIG. 7 is a graph representing the correlation between a ratio of theshift amount SS1 of each of the first and second outer electrodes 21Aand 22A to the length LC of the elementary body 11 and a peak vibrationlevel. FIG. 7 represents the result in the case where the length LD ofeach of the first and second outer electrodes 21A and 22A is about 0.2times the length LC of the elementary body 11, for example.

As seen from FIG. 7, the peak vibration level has a minimum value withrespect to the ratio of the shift amount SS1 of each of the first andsecond outer electrodes 21A and 22A to the length LC of the elementarybody 11. In more detail, as illustrated in FIG. 7, the peak vibrationlevel has a minimum value at SS1=(0.1±0.05)×LC, i.e., when the shiftamount SS1 of each of the first and second outer electrodes 21A and 22Afrom the center position of the elementary body 11 in the lengthwisedirection is about 0.1 times the length LC of the elementary body 11,for example.

Accordingly, the vibration can be reduced to a larger extent by settingthe shift amount SS1 of each of the first and second outer electrodes21A and 22A to be about 0.1 times the length LC of the elementary body11, for example.

In addition, the arrangement (shapes and sizes) of the first and secondouter electrodes may preferably be specified as follows, based on boththe results of FIGS. 5 and 7.

As seen from FIG. 5, the vibration noise is reduced when the length LDof each of the first and second outer electrodes is not more than about0.5 times the length LC of the elementary body 11, for example.

As seen from FIG. 7, the vibration noise is also reduced by shifting thecenter of each of the first and second outer electrodes in thelengthwise direction from the center of the elementary body 11 in thelengthwise direction within the range of about 0.15 times the length LCof the elementary body 11, for example.

In consideration of the results described above, the ends of each of thefirst and second outer electrodes in the lengthwise direction arepreferably arranged to position within the range of about 0.25 times thelength LC of the elementary body 11 from the center of the elementarybody 11 in the lengthwise direction, for example. With such anarrangement, the vibration noise can be reduced to a level not higherthan a level obtained in the case where the center of each of the firstand second outer electrodes in the lengthwise direction is set inalignment with the center of the elementary body and the length LD ofeach of the first and second outer electrodes and is preferably set tobe about 0.5 times the length LC of the elementary body 11, for example.

Accordingly, the first and second outer electrodes are preferablyarranged such that the ends of each of the first and second outerelectrodes in the lengthwise direction are positioned within the rangeof about 0.25 times the length LC of the elementary body 11 from thecenter of the elementary body 11 in the lengthwise direction, forexample.

While preferred embodiments of the present invention have been describedabove in connection with an example in which the first and second outerelectrodes are formed over the full height of the first and secondlengthwise side surfaces, the first and second outer electrodes may eachbe arranged to extend until an intermediate position in the heightdirection from the bottom surface 112 of the elementary body 11.

Furthermore, the first and second outer electrodes may have shapes whichdo not extend in a partly covering relationship with the top surface ofthe elementary body.

When the first and second outer electrodes have shapes extending in apartly covering relationship with the top surface and the bottom surfaceof the elementary body, the vibration noise can be suppressed by settingan amount of the coverage to be as small as possible, taking intoaccount reliability of the mounting. For example, the coverage amount ispreferably set such that the first and second outer electrodes will notoverlap with a region where the inner electrodes 100 layered in thestacking direction are opposed to each other, when looking at theelementary body 11 from above (i.e., when viewed in the directionperpendicular or substantially perpendicular to the top surface 111).

The vibration noise can preferably be more effectively reduced by usingthe monolithic capacitor having the above-described structure asfollows. FIG. 8 is a flowchart illustrating a method for reducing thevibration noise generated from the mounting substrate in accordance witha preferred embodiment of the present invention.

Vibration noise generated from a mounting substrate including aplurality of monolithic capacitors mounted thereon is measured (S101).The vibration noise can be measured, for example, by a method ofdirectly measuring the vibration noise with a microphone, a method ofindirectly measuring the vibration noise by measuring vibration with alaser Doppler vibration meter, etc.

When the vibration noise exceeds a predetermined threshold, a monolithiccapacitor that is a source of generating the vibration noise isspecified (S102).

The monolithic capacitor that is the source of generating the vibrationnoise is replaced with the monolithic capacitor according to thepreferred embodiment of the present invention (S103). At that time, whenpositions where land electrodes arranged to mount the monolithiccapacitor are configured differently from the positions of the first andsecond outer electrodes according to the preferred embodiments of thepresent invention, intermediate substrates arranged to connect the landelectrodes and the first and second outer electrodes may be provided, orintermediate electrode patterns may be defined on the mountingsubstrate, for example. As an alternative, when possible, patterns ofthe land electrodes on the mounting substrate may be modified. It is tobe noted that the threshold for the vibration noise is defined dependingon, e.g., the intended use of an electronic device used in practice.

The vibration noise which was generated prior to the replacement of themonolithic capacitor can be reduced by utilizing the above-describedmethod. An effect of the method of reducing the vibration noise,illustrated in FIG. 8, is experimentally proved for the case using amonolithic capacitor with a length LC=1.0 mm in the lengthwisedirection, a width LCw=0.5 mm in the widthwise direction, and a heightof 0.5 mm, for example. However, the above-described method can also beapplied to monolithic capacitors having other dimensions.

In the monolithic capacitor mounting structures according to the firstand second preferred embodiments of the present invention, as describedabove, the vibration of the mounting substrate is significantly reducedor prevented based on at least one of the relationship between thelength LD of each of the first and second outer electrodes and thelength LC of the elementary body 11, and the relationship between thecenter position of the elementary body 11 in the lengthwise directionand the center position of each of the first and second outer electrodesin the lengthwise direction. Even with the length and the centerposition of each of the first and second outer electrodes being heldfixed, however, the vibration of the mounting substrate can also besignificantly reduced or prevented based on at least one of therelationship between a length of each of the first bonding portion 902and the second bonding portion in the lengthwise direction and thelength LC of the elementary body 11, and the relationship between thecenter position of the elementary body 11 in the lengthwise directionand a center position of each of the first bonding portion 902 and thesecond bonding portion in the lengthwise direction.

For example, a length of each land electrode in the lengthwise directionmay be changed such that the relationship between the length of each ofthe first bonding portion 902 and the second bonding portion in thelengthwise direction and the length LC of the elementary body 11satisfies the above-described condition, and each land electrode may beshifted such that the relationship between the center position of theelementary body 11 in the lengthwise direction and the center positionof each of the first bonding portion 902 and the second bonding portionin the lengthwise direction satisfies the above-described condition. Inmore detail, such a modification may be practiced as follows.

A monolithic capacitor mounting structure according to a third preferredembodiment of the present invention will be described below withreference to the drawings. FIG. 9 is an external perspective view of amounting substrate 90 in the mounting structure according to the thirdpreferred embodiment. FIGS. 10A, 10B, and 10C are three orthogonal viewsof the mounting substrate 90 in the mounting structure according to thethird preferred embodiment. FIG. 11 is a perspective view illustrating astate in which a monolithic capacitor 10B is mounted to the mountingsubstrate 90 in the mounting structure according to the third preferredembodiment.

The monolithic capacitor mounting structure according to the thirdpreferred embodiment is preferably different from the monolithiccapacitor mounting structure according to the first preferred embodimentin shapes of the first and second outer electrodes and shapes of theland electrodes. The other structure is the same and description thereofis omitted here.

The mounting substrate 90 preferably includes an insulating substrate90B in the shape of a flat or substantially flat plate. Land electrodes91B and 92B are preferably defined on one principal surface (frontsurface) of the insulating substrate 90B. The land electrode 91B is anelectrode to which a first outer electrode 23 of the monolithiccapacitor 10B is bonded. The land electrode 92B is an electrode to whicha second outer electrode 24 of the monolithic capacitor 10B is bonded.

The first outer electrode 23 is defined on the first lengthwise sidesurface, extending in the lengthwise direction, of the elementary body11. The second outer electrode 24 is defined on the second lengthwiseside surface, extending in the lengthwise direction, of the elementarybody 11. The first outer electrode 23 and the second outer electrode 24are preferably arranged over the entire first and second lengthwise sidesurfaces, respectively.

The monolithic capacitor 10B having the above-described structure ismounted to the mounting substrate 90, as illustrated in FIG. 11. Morespecifically, the first outer electrode 23 is preferably bonded to theland electrode 91B using a solder 900, and the second outer electrode 24is preferably bonded to the land electrode 92B using a solder 900, suchthat the monolithic capacitor 10B is mounted to a predetermined regionof the mounting substrate 90.

A first bonding portion 902B is a portion of the first outer electrode23 where the first outer electrode 23 is joined with the solder 900. Asecond bonding portion (not shown, but identical or substantiallyidentical to the first bonding portion 902B) is a portion of the secondouter electrode 24 where the second outer electrode 24 is joined withthe solder 900.

As a result of the bonding using the solder 900, the monolithiccapacitor 10B is mounted to the mounting substrate 90 through the firstbonding portion 902B and the second bonding portion.

Even with the arrangement described above, the monolithic capacitor 10Bis mounted, in its regions where the distortion is small, to themounting substrate 90 through the first bonding portion 902B and thesecond bonding portion.

Furthermore, the land electrodes 91B and 92B preferably have sizesdescribed below. It is assumed that a length of each of the landelectrodes 91B and 92B in the lengthwise direction is LE.

FIG. 12 is a graph representing the correlation between a ratio of thelength LE of each of the land electrodes 91B and 92B to the length LC ofthe elementary body 11 and a peak vibration level. FIG. 12 representsthe case where the center of the elementary body 11 in the lengthwisedirection is aligned with a center of each of the land electrodes 91Band 92B in the lengthwise direction.

It is to be noted that, in FIG. 12, REF1 represents the same case asthat represented by REF1 in FIG. 5. Moreover, FIG. 12 represents theresult in the case where the elementary body 11 has the same dimensionsas those of the elementary body 11 in FIG. 5.

As seen from FIG. 12, the peak vibration level can be reduced incomparison with the case of REF1 by setting the length LE of each of theland electrodes 91B and 92B to be shorter than the length LC of theelementary body 11, and by arranging the land electrodes 91B and 92B atthe center of the elementary body 11 in the lengthwise direction.

In addition, as seen from FIG. 12, the peak vibration level preferablyhas a minimum value with respect to the ratio of the length LE of eachof the land electrodes 91B and 92B to the length LC of the elementarybody 11. In more detail, as illustrated in FIG. 12, the peak vibrationlevel has a minimum value at LE=(0.4±0.05)×LC, i.e., when the length LEof each of the land electrodes 91B and 92B preferably is about 0.4 timesthe length LC of the elementary body 11, for example. Furthermore, arange where the vibration attributable to the distortion can be regardedas sufficiently small is within a range of predetermined length LEincluding 0.4 LC and thereabout at which the minimum value is obtained.More specifically, that range is given as a range where the peakvibration level illustrated in FIG. 12 is smaller than a reduced valueTh, i.e., a range where the length LE of each of the land electrodes 91Band 92B preferably is about 0.2 times to about 0.5 times the length LCof the elementary body 11, for example. In the third preferredembodiment, the reduced value Th is set to −10 dB of the peak vibrationlevel in the cases of REF1. The reduced value Th can be increased ordecreased depending on the situation in use of the monolithic capacitor,but a more satisfactory result is obtained by setting the reduced valueTh to −10 dB, for example.

Thus, the vibration can be greatly reduced by setting the length LE ofeach of the land electrodes 91B and 92B to preferably fall in the rangeof about 0.2 times to about 0.5 times the length LC of the elementarybody 11, for example. The vibration can be reduced to a larger extent bysetting the length LE of each of the land electrodes 91B and 92B to beabout 0.4 times the length LC of the elementary body 11, for example.

A monolithic capacitor 10C mounting structure according to a fourthpreferred embodiment of the present invention will be described belowwith reference to the drawings. FIG. 13 is a plan view of a mountingsubstrate 90 which preferably includes an insulating substrate 90C inthe mounting structure according to the fourth preferred embodiment ofthe present invention. The mounting structure according to the fourthpreferred embodiment is preferably different from the mounting structureaccording to the third preferred embodiment in that the positions of theland electrodes 91B and 92B in the lengthwise direction of theelementary body 11 are shifted (displaced). The other arrangement is thesame as that of the mounting substrate 90 according to the thirdpreferred embodiment, and detailed description of the other arrangementis omitted here.

In the mounting substrate 90 illustrated in FIG. 13, centers of the landelectrodes 91C and 92C in the lengthwise direction are shifted from thecenter of the elementary body 11 in the lengthwise direction. An amountSS2 of such center shift preferably is about 0.1±0.05 times the lengthLC of the elementary body 11, for example.

FIG. 14 is a graph representing a vibration noise suppression effect ofthe mounting substrate 90. FIG. 14 represents the result in the casewhere the length LE of each of the land electrodes 91C and 92Cpreferably is about 0.2 times the length LC of the elementary body 11 ofthe monolithic capacitor 10B.

As seen from FIG. 14, the peak vibration level has a minimum value withrespect to a ratio of the shift amount SS2 of each of the landelectrodes 91B and 92B to the length LC of the elementary body 11. Inmore detail, as illustrated in FIG. 14, the peak vibration level has aminimum value at SS2=(0.1±0.05)×LC, i.e., when the shift amount SS2 ofeach of the land electrodes 91B and 92B from the center position of theelementary body 11 in the lengthwise direction preferably is about 0.1times the length LC of the elementary body 11, for example.

Accordingly, the vibration can be reduced to a larger extent by settingthe shift amount SS2 of each of the land electrodes 91B and 92B to beabout 0.1 times the length LC of the elementary body 11, for example.

In addition, the arrangement (positions and shapes) of the landelectrodes may be specified as follows, based on both the results ofFIGS. 12 and 14.

As seen from FIG. 12, the vibration noise is reduced when the length LEof each land electrode preferably is not more than about 0.5 times thelength LC of the elementary body 11, for example.

As seen from FIG. 14, the vibration noise is also reduced by shiftingthe center of each land electrode in the lengthwise direction from thecenter of the elementary body 11 in the lengthwise direction preferablywithin the range of about 0.15 times the length LC of the elementarybody 11, for example.

In consideration of the results described above, the ends of each landelectrode in the lengthwise direction are arranged to position withinthe range of about 0.25 times the length LC of the elementary body 11from the center of the elementary body 11 in the lengthwise direction.With such an arrangement, the vibration noise can preferably be reducedto a level not higher than a level obtained in the case where the centerof each land electrode in the lengthwise direction is set in alignmentwith the center of the elementary body and the length LE of each landelectrode is preferably set to be about 0.5 times the length LC of theelementary body 11, for example.

Accordingly, the land electrodes are preferably arranged such that theends of each land electrode in the lengthwise direction are positionedwithin the range of about 0.25 times the length LC of the elementarybody 11 from the center of the elementary body 11 in the lengthwisedirection, for example.

The vibration noise can be more effectively reduced by including themounting substrate, which includes the land electrodes having theabove-described structure, as follows. FIG. 15 is a flowchartillustrating a method for reducing the vibration noise generated fromthe mounting substrate in accordance with a preferred embodiment of thepresent invention.

Vibration noise generated from a mounting substrate including aplurality of monolithic capacitors mounted thereon is measured (S201).The vibration noise can preferably be measured by, for example, a methodof directly measuring the vibration noise with a microphone, a method ofindirectly measuring the vibration noise by measuring vibration with alaser Doppler vibration meter, etc.

When the vibration noise exceeds a predetermined threshold, the mountedposition of a monolithic capacitor that is a source of generating thevibration noise is specified (S202).

Land electrode patterns of the monolithic capacitor that is the sourceof generating the vibration noise is replaced with the land electrodepatterns according to a preferred embodiment of the present invention(S203). In practice, for example, a conversion substrate or conversionpatterns arranged to convert the land electrode patterns on the mountingsubstrate under the measurement to the land electrode patterns accordingto a preferred embodiment of the present invention may be disposedbetween the mounting substrate and the monolithic capacitor.Alternatively, when possible, the land electrode patterns on themounting substrate may be modified. It is to be noted that the thresholdfor the vibration noise is preferably defined depending on, e.g., theintended use of an electronic device used in practice.

The vibration noise having generated prior to the replacement of theland electrode patterns can be reduced by utilizing the above-describedmethod. An effect of the method of reducing the vibration noise,illustrated in FIG. 15, is experimentally proved for the case using amonolithic capacitor with a length LC=1.0 mm in the lengthwisedirection, a width LCw=0.5 mm in the widthwise direction, and a heightof 0.5 mm, for example. However, the above-described method can also beapplied to monolithic capacitors having other dimensions.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A monolithic capacitor mounting structurecomprising: a monolithic capacitor including an elementary body having aparallelepiped shape or a substantially parallelepiped shape and definedby plural dielectric layers and plural inner electrodes, which arealternately stacked, only one first outer electrode located on a firstside surface, extending in a lengthwise direction, of the elementarybody, and only one second outer electrode located on a second sidesurface, extending in the lengthwise direction, of the elementary body;a mounting substrate including an insulating substrate, a first landelectrode disposed on a surface of the insulating substrate andconnected to the first outer electrode, and a second land electrodedisposed on the surface of the insulating substrate and connected to thesecond outer electrode; a first bonding material arranged to bond thefirst outer electrode and the first land electrode; and a second bondingmaterial arranged to bond the second outer electrode and the second landelectrode; wherein a portion of the first outer electrode joined withthe first bonding material is a first bonding portion and a portion ofthe second outer electrode joined with the second bonding material is asecond bonding portion; a length of each of the first and second bondingportions in the lengthwise direction is about 0.2 times to about 0.5times a length of the elementary body in the lengthwise direction; and acenter of each of the first and second bonding portions in thelengthwise direction is located at a position different from a center ofthe elementary body in the lengthwise direction.
 2. The monolithiccapacitor mounting structure according to claim 1, wherein the length ofeach of the first and second bonding portions in the lengthwisedirection is within a range of about 0.4±0.05 times the length of theelementary body in the lengthwise direction.
 3. The monolithic capacitormounting structure according to claim 2, wherein a length of each of thefirst and second land electrodes in the lengthwise direction is within arange of about 0.4±0.05 times the length of the elementary body in thelengthwise direction.
 4. The monolithic capacitor mounting structureaccording to claim 1, wherein the first and second bonding portionsextending in the lengthwise direction are arranged such that ends ofeach of the first and second bonding portions in the lengthwisedirection are positioned within a range of about 0.25 times the lengthof the elementary body in the lengthwise direction from the center ofthe elementary body in the lengthwise direction.
 5. The monolithiccapacitor mounting structure according to claim 4, wherein the first andsecond outer electrodes are arranged such that ends of each of the firstand second outer electrodes in the lengthwise direction are positionedwithin a range of about 0.25 times the length of the elementary body inthe lengthwise direction from the center of the elementary body in thelengthwise direction.
 6. The monolithic capacitor mounting structureaccording to claim 4, wherein the first and second land electrodes arearranged such that ends of each of the first and second land electrodesin the lengthwise direction are positioned within a range of about 0.25times the length of the elementary body in the lengthwise direction fromthe center of the elementary body in the lengthwise direction.
 7. Themonolithic capacitor mounting structure according to claim 1, wherein adistance between the center of each of the first and second bondingportions in the lengthwise direction and the center of the elementarybody in the lengthwise direction is within a range of about 0.1±0.05times the length of the elementary body in the lengthwise direction. 8.The monolithic capacitor mounting structure according to claim 7,wherein a distance between the center of each of the first and secondouter electrodes in the lengthwise direction and the center of theelementary body in the lengthwise direction is within a range of about0.1±0.05 times the length of the elementary body in the lengthwisedirection.
 9. The monolithic capacitor mounting structure according toclaim 7, wherein a distance between a center of each of the first andsecond land electrodes in the lengthwise direction and the center of theelementary body in the lengthwise direction is within a range of about0.1±0.05 times the length of the elementary body in the lengthwisedirection.
 10. The monolithic capacitor mounting structure according toclaim 1, wherein the length of each of the first and second outerelectrodes in the lengthwise direction is about 0.2 times to about 0.5times the length of the elementary body in the lengthwise direction; anda center of each of the first and second outer electrodes in thelengthwise direction is located at a position different from the centerof the elementary body in the lengthwise direction.
 11. The monolithiccapacitor mounting structure according to claim 1, wherein the length ofeach of the first and second outer electrodes in the lengthwisedirection is within a range of about 0.4±0.05 times the length of theelementary body in the lengthwise direction.
 12. The monolithiccapacitor mounting structure according to claim 1, wherein a length ofeach of the first and second land electrodes in the lengthwise directionis about 0.2 times to about 0.5 times the length of the elementary bodyin the lengthwise direction; and a center of each of the first andsecond land electrodes in the lengthwise direction is located at aposition different from the center of the elementary body in thelengthwise direction.
 13. The monolithic capacitor mounting structureaccording to claim 1, wherein the first bonding material and the secondbonding material are both a solder.
 14. A monolithic capacitorcomprising: an elementary body having a parallelepiped shape or asubstantially parallelepiped shape and defined by plural dielectriclayers and plural inner electrodes, which are alternately stacked, onlyone first outer electrode located on a first side surface, extending ina lengthwise direction, of the elementary body, and only one secondouter electrode located on a second side surface, extending in thelengthwise direction, of the elementary body; wherein a length of eachof the first and second outer electrodes in the lengthwise direction isabout 0.2 to times to about 0.5 times a length of the elementary body inthe lengthwise direction; and a center of each of the first and secondouter electrodes in the lengthwise direction is located at a positiondifferent from a center of the elementary body in the lengthwisedirection.
 15. The monolithic capacitor according to claim 14, whereinthe length of each of the first and second outer electrodes in thelengthwise direction is within a range of about 0.4±0.05 times thelength of the elementary body in the lengthwise direction.
 16. Themonolithic capacitor according to claim 14, wherein the first and secondouter electrodes are arranged such that ends of each of the first andsecond outer electrodes in the lengthwise direction are positionedwithin a range of about 0.25 times the length of the elementary body inthe lengthwise direction from the center of the elementary body in thelengthwise direction.
 17. The monolithic capacitor according to claim14, wherein a distance between the center of each of the first andsecond outer electrodes in the lengthwise direction and the center ofthe elementary body in the lengthwise direction is within a range ofabout 0.1±0.05 times the length of the elementary body in the lengthwisedirection.
 18. A monolithic capacitor mounting structure comprising: amonolithic capacitor including an elementary body having aparallelepiped shape or a substantially parallelepiped shape and definedby plural dielectric layers and plural inner electrodes, which arealternately stacked, only one first outer electrode located on a firstside surface, extending in a lengthwise direction, of the elementarybody, and only one second outer electrode located on a second sidesurface, extending in the lengthwise direction, of the elementary bodyextending in the lengthwise direction thereof; a mounting substrateincluding an insulating substrate, a first land electrode disposed on asurface of the insulating substrate and connected to the first outerelectrode, and a second land electrode disposed on the surface of theinsulating substrate and connected to the second outer electrode;wherein a length of each of the first and second land electrodes in thelengthwise direction is about 0.2 times to about 0.5 times a length ofthe elementary body in the lengthwise direction; and a center of each ofthe first and second land electrodes in the lengthwise direction islocated at a position different from a center of the elementary body inthe lengthwise direction.
 19. The monolithic capacitor mountingstructure according to claim 18, wherein the length of each of the firstand second land electrodes in the lengthwise direction is within a rangeof about 0.4±0.05 times the length of the elementary body in thelengthwise direction.
 20. The monolithic capacitor mounting structureaccording to claim 18, wherein each of the first and second landelectrodes have a same or substantially a same length and are arrangedat a same or substantially a same position in the lengthwise direction.